Recovery of locomotion from permanent paralysis caused by spinal cord injuries (SCI) is one of the biggest topics in spinal cord prosthesis. It is known that networks of neurons in the lumbosacral spinal cord retain an intrinsic capability to oscillate and generate coordinated rhythmic motor outputs Circuits underlying such rhythmic and oscillatory outputs are commonly referred as central pattern generators (CPGs) (Grinner (2006) Neuron, 52: 751-766). Studies have demonstrated that animals can regain motor control from the plasticity of the spinal cord (Lavrov et al. (2006) J. Neurophysiol. 96: 1699-1710), and regain movements including, but not limited to, stepping and standing by stimulating the CPGs without control from the brain (Gad et al. (2013) J. Neuroengin. & Rehabil., 10: 2).
To provide the stimulus patterns into the spinal cord, various electrode arrays have been developed (see, e.g., Gad et al. (2013) J. Neuroengin. & Rehabil., 10: 2; Nandra et al. (2011). A parylene-based microelectrode array implant for spinal cord stimulation in rats,” in Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference, pp. 1007-1010).